1. Field of the Invention
The present invention relates to a display device which estimates a temperature of a display panel using a temperature sensor, and more particularly to a technique for enhancing the accuracy of temperature estimation.
2. Description of the Related Art
Various devices which constitute heat sources such as a backlight unit, a power source circuit and a drive circuit for a liquid crystal display panel are arranged in the inside of a housing of a liquid crystal display device. The operation of liquid crystal is affected by heat generated from the heat sources. Conventionally, there has been known a liquid crystal display device where a temperature sensor is arranged in the inside of a housing, and a temperature of a liquid crystal display panel is calculated based on a temperature detected by the temperature sensor (see JP 2000-89197 A and JP 2007-93939 A, for example). In these liquid crystal display devices, a gray scale value is corrected based on a temperature of the liquid crystal display panel.
A temperature of the above-mentioned device which constitutes the heat source is changed corresponding to a drive state of the liquid crystal display device. For example, there has been known a liquid crystal display device which has a high brightness mode and a low brightness mode as an operation mode of a backlight unit. In such a liquid crystal display device, when the operation mode is switched to the low brightness mode from the high brightness mode, for example, a temperature of the backlight unit is gradually lowered. However, since it is difficult to mount the temperature sensor on a liquid crystal display panel per se, it is often the case that the temperature sensor is disposed away from the liquid crystal display panel. Accordingly, although a temperature of the liquid crystal display panel and an output value of the temperature sensor are changed in accordance with a change in temperature of a heat source, there exists a time lag between a change in temperature of the liquid crystal display panel and a change in output value of the temperature sensor. Accordingly, when a temperature of the heat source is changed, an difference between a temperature of the liquid crystal display panel calculated using the temperature sensor and an actual temperature of the liquid crystal display panel is increased due to the above-mentioned time lag.